Tried the various remedies to clean off the head on impact of stuff over the past 17-18 years, none worked (for me).Think it has something to do with the type of lense material and the heat of the lamp. Oddly, the turn signal/park and side marker lenses look new without touching. So,figured WTH, I'd try something before purchasing news ones. The following seemed to work fine.

1) cutoff the 3 nibs/nubs, whatever they're called with wire cutters
***Used 4x4 vibrating sander (I've had forever), masking the other (2) lights.with several layers of duct tape.
2) 220 grit, till the lense felt like 220
3) 400 grit, till the lense felt like 400
4) 800 grit, till...................................was going to follow up with 1200/1500, $13, nevermind.
***Up until now, could see reflectors just a little bit. Was not to encouraging until the last step.
Last) Used "swirl remover" from Stewmac I use on guitar bodies, with buffing cone and drill. It's just a micro polishing compound that leaves zero swirl marks.

Note: Did not remove lights from the leveling/aiming cradle, just removed the 3 mounting bolts. Hopefully that was sufficient enoough to avoid re-adjustment for aim/leveling.

"I'll be spending that money elsewhere.

 

You need to apply some flavor of UV protectant to the lens, else they will fog again in fairly short order.

The headlights on my Rams looked like that too. I just replaced the headlight assemblies. Got 'em from A-MAutoparts.com, (or something like that.) They fit just like OEM, and the first set still looked brand new 7 years later, when I sold the truck.

 

They look great. I'd apply some carnauba wax every month or two. That might keep em from fogging again.